CRABS AND SHRIMPS 



213- 



supplied with filtered water, that all insects might be re- 

 moved; but in about an hour the same creatures were ob- 

 served swimming about as before. To render the matter, 

 if possible, still more certain, some of the ova were opened, 

 and the embryos extracted ; but shortly afterward I had the 

 pleasure of witnessing, beneath the microscope, the natural 

 bursting and escape of one precisely similar in form to 

 those found so abundantly in the water. Thus, then, 

 there is no doubt that these grotesque-looking creatures 

 are the young of the Garcinus 

 mcenas; but how different they 

 are from the adult need hard- 

 ly be pointed out any further 

 than by referring to the figure. 

 When they first escape they 

 rarely exceed half a line in 

 length. The body is ovoid, 

 the dorsal shield large and in- 

 flated; on its upper edge and 

 about the middle is a long 

 spine, curved posteriorly, and 

 rather longer than the diam- 

 eter of the body, though it 

 varies in length in different specimens; it is hollow, and 

 the blood may be seen circulating through it. The upper 

 portion of the body is sap-green, and the lower semi- 

 transparent. The eyes are large, sessile, and situated in 

 front, and the circumference of the pupil is marked with 

 radiating lines. The lower margin of the shield is waved, 

 and at its posterior and lateral margin is a pair of natatory 

 feet. The tail is extended, longer than the diameter of the 

 shield; and is composed of five equal annulations, besides 



ZOEA OP SHORE-CRAB. 



